Tin tetrachloride → Methyl 3-amino-1H-thieno[3,2-c]pyrazole-5-carboxylate

HRID 1723919Notes

Reaction equation

HRID 1723919 reaction equation
[C:1]([C:3]1[S:7][C:6]([C:8]([O:10][CH3:11])=[O:9])=[CH:5][C:4]=1[N+:12]([O-])=O)#[N:2].[N:15]([O-])=O.[Na+].[Sn](Cl)(Cl)(Cl)Cl>Cl.O>[NH2:2][C:1]1[C:3]2[S:7][C:6]([C:8]([O:10][CH3:11])=[O:9])=[CH:5][C:4]=2[NH:12][N:15]=1

Participants

6

Reactant 3

HCID 24287Tin tetrachlorideHCID 23668193Sodium NitriteHCID 68828210Methyl 5-cyano-4-nitrothiophene-2-carboxylate

Product 1

HCID 44558323Methyl 3-amino-1H-thieno[3,2-c]pyrazole-5-carboxylateYield 37%

Reagents, catalysts & solvents 2

HCID 313Hydrochloric AcidSolvent2×HCID 962WaterSolvent

Procedure

To an ice-cooled suspension of methyl 5-cyano-4-nitro-thiophene-2-carboxylate (0.10 mol, 21.0 g) in 120 mL of hydrochloric acid 37% was added, dropwise, a solution of sodium nitrite (0.12 mol, 8.3 g) in 12 mL of water. After 1.5 hours, the cold suspension was added dropwise to a preformed solution of tin chloride (0.80 mol, 151.7 g) in 120 mL of hydrochloric acid 37%, at 5° C. After 3 hours, the cold suspension was filtered and the moist solid was treated with 350 mL of boiling water, for 30 min. The hot cloudy solution was clarified by filtration through a cloth filter. The liquors were ice-cooled and treated, dropwise, with 180 mL of sodium hydroxide 17%. The obtained solid was filtered off and dried, under vacuum, at 50° C., to give 7.3 g of the title compound as a yellow solid (37% yield).

Workup

  1. additionwas added
  2. waitAfter 3 hours
  3. filtrationthe cold suspension was filtered
  4. additionthe moist solid was treated with 350 mL of boiling water, for 30 min
  5. filtrationThe hot cloudy solution was clarified by filtration through a cloth
  6. filtrationfilter
  7. temperaturecooled
  8. additiontreated
  9. filtrationThe obtained solid was filtered off
  10. customdried, under vacuum, at 50° C.

Sources & evidence

ORD record
ord-023931786c22485295153653477ba338
Source dataset
uspto-grants-2009_02
Patent number
US07485661B2

Reaction notes

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